[1] He and his family spent four years in the Kakuma refugee camp in Kenya before moving to Sydney, Australia, where he was introduced to basketball by his high school teacher.
[8] On 31 October 2016, Atem signed with the Goldfields Giants for the 2017 State Basketball League season.
[10][11] In December 2017, Atem signed with the North Adelaide Rockets for the 2018 season, returning to the Premier League for a second stint.
[16] In 2020, Atem played for the South West Metro Pirates in the Queensland State League (QSL).
[23] In March 2017, Atem played for the South Sudanese national team at the FIBA AfroBasket 2017 qualifiers.